ECT (Edge Crush Test) and Mullen (burst test) are the two historical standards for rating corrugated board strength — but they measure different failure modes.
Short answer: Use ECT for most ecommerce shippers, retail case packs, and pallet stacking. Use Mullen when a buyer still writes “# test,” or when face puncture from sharp/heavy contents is the real risk. BoxYourBrand engineers corrugated shipping boxes and mailer boxes to ECT targets matched to channel — request a free packaging quote with pallet height and unit weight.
This guide compares ECT vs Mullen and helps you spec the right corrugated grade.
Key takeaways
- ECT measures stacking strength — primary spec for warehouse and pallet freight.
- Mullen measures burst/puncture resistance — relevant for sharp or heavy contents and legacy specs.
- Higher ECT generally means stronger stack but also affects board weight and cost.
- Share pallet pattern and handling chain when quoting case packs — not just product weight.
What is ECT?
Edge Crush Test (ECT) compresses a small sample of corrugated standing on its edge until failure. Result is reported in ** pounds per inch (lb/in)** — common ratings include 32 ECT, 44 ECT, and 55 ECT on single-wall board.
ECT correlates with box compression strength — how much weight can sit on top of a closed RSC in a warehouse stack or trailer. Retail CPG buyers, 3PLs, and club-store vendors routinely specify minimum ECT on master shippers and case packs.
Pair ECT selection with flute type — see corrugated flute types explained for A/B/C/E profiles.
What is Mullen burst test?
Mullen test (burst strength) applies increasing hydraulic pressure to the flat face of corrugated until it ruptures. Result in ** pounds per square inch (psi)** — historically labeled as “# Mullen” (e.g., 200# test).
Mullen emphasizes puncture and rough handling — relevant when contents have sharp edges, when boxes slide on abrasive surfaces, or when legacy purchase orders still cite Mullen instead of ECT.
ECT vs Mullen comparison
| Factor | ECT | Mullen (burst) |
|---|---|---|
| Measures | Edge stacking strength | Face puncture resistance |
| Common use today | Parcel shippers, case packs, pallets | Legacy specs, heavy/ sharp contents |
| Buyer specs | Retail CPG, 3PL, club | Some industrial accounts |
| Correlates with | Stack height in DC | Rough handling abuse |
| Typical quote language | “44 ECT single wall” | “200# Mullen test” |
Many modern boards are engineered for ECT performance with lighter liners than old Mullen-equivalent boxes — do not assume “# test” converts 1:1 to ECT without supplier data.
Choosing strength for your channel
Ecommerce parcel (DTC):
- Single-item shippers: often 32 ECT single-wall when product under ~30 lbs and stack height modest.
- Heavy or fragile: 44 ECT or double-wall — see custom corrugated box types guide.
Retail case packs / LTL:
- Master shippers: 44–55+ ECT depending on pallet height and case weight.
- Document units per case, case weight, pallet pattern — explore retail CPG packaging.
Mailer boxes (E-flute):
- ECT still applies but mailers prioritize print surface and caliper — structural spec differs from C-flute RSC.
Use the box size calculator and share packed weight with quote request.
Double-wall and combination grades
Double-wall corrugated (e.g., BC flute combination) adds ECT and puncture margin for electronics, glass case packs, and high-stack pallet programs. Specify double-wall when:
- Pallet exceeds 48“ stack with heavy cases
- Contents are fragile multi-unit glass or liquids
- Buyer spec sheet mandates burst and stack margins beyond single-wall
Read custom electronics packaging guide for insert and outer box pairing.
Ordering with strength specs
Provide product weight, case pack count, pallet diagram, and buyer ECT/Mullen minimum if applicable. BoxYourBrand confirms board grade against your handling chain before production. Order corrugated samples to validate caliper and print before MOQ lock.
See packaging glossary — ECT, RSC, dieline for related terminology.
